Characterization of additively manufactured parts for direct screwing

The combination of additive manufacturing and direct screwing can minimize the limitations in additive manufacturing such as long manufacturing times and high costs for expanding building spaces. Direct screwing allows smaller components to be assembled into larger components and attachable to assemblies with high functional integration. Thus, large building spaces can be avoided, and integration of additive components into serial production is possible. Although there are guidelines for direct screwing of injection-molded thermoplastic components by the Deutscher Verein fur Schweissen und verwandte Verfahren e.V. (German Welding Society), there are currently no recommendations that can be directly applied to additively manufactured components. The layered manufacturing process of additively manufactured components is highly anisotropic as the strength of the components strongly depends on the build orientation. Thus, the compatibility of additive manufactured components for direct screwing was investigated at the Kunststofftechnik Paderborn. The characterization of additively manufactured screw bosses was considered with respect to the existing guidelines. For the characterization, screw domes were additively manufactured according to the geometry recommendations of the guidelines with the fused deposition modeling and the selective laser sintering. To account for the anisotropy, the screw domes were built in three different orientations. The compatibility of additively manufactured screw domes was evaluated through a comparison to injection-molded screw bosses. For the comparison, the joining parameters, the pull-out strength, and the component strength were investigated. The results showed there are significant differences in the investigated criteria based on the manufacturing technique and the build orientation.